We have previously shown that antibody titres to several heat-shock proteins (Hsps) are elevated in dyslipidaemic patients and subjects with established vascular disease. Obesity is known to be associated with raised serum inflammatory markers suggesting a state of heightened immune activation. Hence, we have investigated the association between indices of obesity and several Hsp antibody titres in healthy subjects. Subjects (n ¼ 170) were recruited from among employees at the University of Surrey and the Royal Surrey County Hospital, Guildford, UK. Of these subjects, 35 were obese with a body mass index (BMI)X30 kg/m 2 (19 male and 16 female subjects), 58 were overweight with 304BMIX25 kg/m 2 (36 male and 22 female subjects) and 77 were of a normal weight with BMIo25 kg/m 2 (31 male and 46 female subjects). Overall, obese subjects had significantly higher plasma anti-Hsp-60 (Po0.001), anti-Hsp-65 (Po0.05) and anti-Hsp-70 (Po0.05) compared with overweight and normal weight subjects.